Soaring costs for dozens of common drugs are forcing Minnesotans to skip or skimp on their medications, causing alarm among doctors who say that the price of prescriptions has become a chronic health problem in and of itself.

The cost of doxycycline, a generic antibiotic, rose from 24 cents per unit in 2011 to $2.21 cents in 2015, while the cost of Avonex, a multiple sclerosis drug, increased from $778 to $5,129 per unit, according to a Star Tribune review of the latest Medicare Part D drug spending data.

Prices for essential drugs such as inhaled albuterol for asthma have spiked as well.

The result has been more patients struggling with illnesses and belatedly admitting that they cut back on prescriptions, said Dr. Macaran Baird, a University of Minnesota physician who has studied the trend for the Minnesota Medical Association and as board chairman for the UCare senior health plan.

"We think they're taking a certain dose, and they're not," he said. "And then they come in [with conditions that are] out of control. And they are ashamed and embarrassed."

The problem has received uneven attention from federal officials, even though 60 percent of respondents in a national tracking poll in April by the Kaiser Family Foundation said that lowering drug costs should be a top priority. President Donald Trump declared, "I'm going to bring down drug prices" a month before taking office, but he hasn't offered legislation. Health care bills in the U.S. House and Senate don't address the issue either.

However, a variety of state organizations are scrutinizing the underlying reasons — which include brand-name manufacturers extending patents and buying out competitors, generic manufacturers raising prices on old medications, and the incentive structures at pharmacy benefit managers and pharmacies.

From 2012 to 2015, private insurance spending on take-home prescriptions increased 21 percent, according to a Minnesota Community Measurement study, from $70 per patient per month to $85. Pharmacy costs surpassed inpatient hospital costs for the first time in 2014, the study showed.

"The prices have gone up so astronomically and no one can dispute it anymore," said U.S. Sen. Amy Klobuchar, D-Minn. "It's really hard to [dispute] when prices for four of the nation's top 10 drugs have increased more than 100 percent in the last five years."

Klobuchar co-authored bills that would, among other things, prevent brand-name companies from paying generic manufacturers to not compete on certain drugs.

Sarah Groen is a pharmacist with HealthPartners' medication therapy management program, which receives referrals from doctors whose patients can't afford their drugs. She recalls a 9-year-old boy who was struggling with breathing because his family couldn't afford inhalers.

"It's very frustrating to see patients who want to be adherent with their medications who can't be because of cost," she said. In the boy's case, a charitable grant is helping the family obtain inhalers for now and keeping his asthma in check. But Groen is seeing more and more patients struggling.

A spike in the price of lidocaine, a generic pain reliever, prompted Groen to move patients to over-the-counter versions that contain almost as much of the active pain-relieving ingredient as the prescription version. Data from Medicare's Part D program, which provides drug coverage for U.S. senior citizens, shows that lidocaine's per-unit cost jumped from 55 cents in 2011 to $5.83 in 2015.

What's driving the spikes?

Brand-name medications have always been more expensive, especially when they first receive federal approval. Harvoni was introduced in 2014 as a cure for hepatitis C infections. The next year, Medicare spent $7 billion on the drug — at a cost of nearly $93,000 per patient who received it.

Other factors have driven costs higher, including generic manufacturers raising prices on drugs for which they have few competitors.

Klobuchar urged congressional intervention last summer after the drugmaker Mylan increased the price of EpiPen injectable drugs, which allergy patients need for emergencies, by 400 percent. In December, two executives at Heritage Pharmaceuticals were convicted of trying to fix the prices of doxycycline as well as glyburide, a diabetes medication.

Trade associations for the brand-name and generic drug manufacturers did not comment for this story. However, officials with Pharmaceutical Research and Manufacturers of America have argued that placing restrictions to help lower costs could reduce drug choices for patients, and that drug revenue helps pay for research of the next generation of treatments.

To drive home its point, the trade group said in a recent blog post that a drug that could delay the onset of Alzheimer's disease by five years could save the U.S. health care system $376 billion.

Doctors weigh in

Baird laid some of the blame on pharmacy benefit managers, which administer prescription drug claims for insurance companies. Conducting research on the rising drug claims paid by UCare, Baird said he was dismayed at how often pharmacy benefit managers accepted deep discounts on brand-name drugs even though they could have saved insurers more money by steering patients to cheaper or generic options.

The Minnesota Medical Association recently approved a plan assembled by a group of its physicians for cutting drug costs. It called for more state oversight of pharmacy benefit managers and transparency regarding their profits.

Baird said the association also wants to prohibit manufacturer coupons, which seem like a good deal to patients initially. But insurers still pay their full share for those brand-name drugs, which results in higher premiums; and patients get used to the brand-name versions and eventually pay the full costs for them, he argued.

Switching patients to generics was a successful strategy in recent years, but one study estimated that 81 percent of patients are now choosing generics on their own, so future savings are limited.

Some generic drugs are now almost as expensive as brand-name rivals, said Carolyn Pare of the Minnesota Health Action Group, a nonprofit that is examining drug prices on behalf of large employers. She recently picked up an expensive prescription and discovered that it was a generic version that was more expensive than the brand-name drug.

"Right now, the patient doesn't know how much something costs, and the doctor doesn't know how much something costs," she said. "That's why groups like ours have to dig into the supply chain" to provide information.

Rising costs also reflect, in part, broader use of prescriptions. The expansion of health insurance under the 2010 Affordable Care Act allowed more people to see doctors, which resulted in more prescriptions.

Baird said doctors need to scrutinize when prescriptions are necessary. Antidepressants, in particular, are overused for episodic instances of depression rather than chronic ones, he said.

And organizations that once promoted generic drugs are now switching focus and helping patients decide whether they need prescriptions at all. The Consumer Reports website now features articles encouraging patients to try talk therapy before antidepressants, for example, and advising which patients can skip preventive medications for high blood pressure.

"Our Best Buy Drugs program is changing," said Consumer Reports' Doris Peter, "into the Don't Do That Drug program."